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1,092 human genomes sequenced to determine standard range of human genetic variation

Thursday, 01 November 2012

Stars mark the 14 populations throughout the world that donated DNA for this study. Credit: Catherine Kolf

Completing the second phase of the 1000 Genomes Project, a multinational team of scientists reports that they have sampled a total of 1092 individuals from 14 different populations and sequenced their full genomes. The researchers described the feat as a collegial effort to equip biologists and physicians with information that can be used to understand the normal range of human genetic variants so that a patient's disease genome can be interpreted in a broader context.

A report on the research, published online in Nature on Nov. 1 represents the culmination of five years of work, says Aravinda Chakravarti, Ph.D., professor of medicine and pediatrics and a member of the Institute of Genetic Medicine at the Johns Hopkins School of Medicine. Chakravarti helped to design the population genetics sampling plan.

"The DNA donors in the study were not known to have any diseases, so the study gives us the genomic background we need for understanding which genetic variations are 'within the normal range,'" Chakravarti says. "With this tool, scientists now have a standard with which they can compare the genome of someone with diabetes, for example." That in turn, Chakravarti says, will increase opportunities for understanding the disease and creating targeted, individualized treatment.

The selection of the 14 populations sampled was based on their ancient migratory history and their genetic relationship to the other populations studied. Within each population, healthy, unrelated donors were randomly chosen for blood draws. The blood samples were first transformed into cell lines that can be stored and grown indefinitely so that they will always be available for future studies. After cell lines were grown, the DNA was sequenced and added to a public database.

The first human genome to be sequenced, published in 2003, made clear that as much as 98.5 percent of human genetic material does not encode proteins, as had been thought. Scientists now know the role of some of the non-protein-coding regions and, although much of the genome remains a mystery, there is reason to suspect that at least some of it plays a part in the variability seen in disease susceptibility and prevalence.